PLAYFAIR, JOHN, an eminent
natural philosopher and mathematician, was the eldest son of James Playfair,
minister of Benvie, in Forfarshire, where he was born on the 10th of March,
1748. He was educated at home until he reached the age of fourteen, when he
was sent to the university of St Andrews, where it was intended that he
should study for the Scottish church. The precocity of talent exhibited by
great men, generally so ill authenticated, has been strikingly vouched by
two remarkable circumstances in the early history of Playfair. While a
student at St Andrews, professor Wilkie, the author of the "Epigoniad," when
in bad health, selected him to deliver lectures on natural philosophy to the
class; and in the year 1766, when only eighteen years of age, he felt
himself qualified to compete as a candidate for the chair of mathematics in
the Marischal college of Aberdeen. In this, his confidence in his powers was
justified by the event. Of six candidates, two only excelled him,—Dr Trail,
who was appointed to the chair, and Dr Hamilton, who afterwards succeeded to
it. [Vide Life of Robert Hamilton in this collection.]

In 1769, having finished his
courses at the university, Mr Playfair lived for some time in Edinburgh, in
the enjoyment of the very select literary society of the period. "It would
appear," says his biographer, [His nephew, by whom a Life of Mr Playfair was
prefixed to an edition of his works, published in 1822.]"from
letters published in the ‘Life of the late Principal Hill,’ that, during
this time, Mr Playfair had twice hopes of obtaining a permanent situation.
The nature of the first, which offered itself in 1769, is not there
specified, and is not known to any of his own family; the second, was the
professorship of natural philosophy in the university of St Andrews, vacant
by the death of his friend Dr Wilkie, which took place in 1772. In this,
which he earnestly desired, and for which he was eminently qualified, he was
disappointed." During the same year, his father died, and the care of his
mother, and of the education of his father’s young family, rendered the
acquisition of some permanent means of livelihood more anxiously desirable.
He was immediately nominated by lord Gray to his father’s livings of Liff
and Benvie; but the right of presentation being disputed, he was unable to
enter on possession, until August, 1773. From that period, his time was
occupied in attending to the duties of his charge, superintending the
education of his brothers, and prosecuting his philosophical studies. In
1774, he made an excursion to Perthshire, to witness the experiments of Dr
Maskelyne, the astronomer royal, to illustrate the principles of
gravitation, from the effect of mountains in disturbing the plumb line. A
permanent friendship was at that time formed between the two philosophers.
"I met," says Playfair, in his Journal of a visit to London in 1782, "with a
very cordial reception from him (Dr Maskelyne), and found that an
acquaintance contracted among wilds and mountains is much more likely to be
durable than one made up in the bustle of a great city: nor would I, by
living in London for many years, have become so well acquainted with this
astronomer, as I did by partaking of his hardships and labours on
Schehallien for a few days."

In 1779, Playfair’s first
scientific effort was given to the public, in "An Essay on the Arithmetic of
Impossible Quantities," published in the sixty-eighth volume of the
Philosophical Transactions. In 1782, an advantageous offer prompted him to
give up his living, and become tutor to Mr Ferguson of Raith and his brother
Sir Ronald Ferguson. It was at this period that he paid the visit to London
in which he met Dr Maskelyne. By that gentleman he was introduced to some
literary men, and to institutions of literary or philosophical interest.
Some of these roused the calm enthusiasm for philosophical greatness which
was one of the principal features of his character. "This," he says, "was
the first time that I had seen the Observatory of Greenwich, and I entered
with profound reverence into that temple of science, where Flamstead, and
Halley, and Bradley, devoted their days and their nights to the
contemplation of the Heavens. The shades of these ancient sages seemed still
to hover round their former mansions, inspiring their worthy successor with
the love of wisdom, and pointing out the road to immortality."

From his thirst after
knowledge being untainted by political or local prejudices, Playfair had
early turned himself to the important discoveries of the continental
algebraists, and was the first man of eminence to introduce them to British
notice. He perceived the prejudices entertained on the subject in England,and probably the discovery sharpened his appetite for a subject which he
found was almost untouched. Speaking of Dr Maskelyne, he says, "He is much
attached to the study of geometry, and I am not sure that he is very deeply
versed in the late discoveries of the foreign algebraists. Indeed, this
seems to be somewhat the case with all the English mathematicians: they
despise their brethren on the continent, and think that everything great in
science must be for ever confined to the country that produced Sir Isaac
Newton." in the works of the eminent natural philosopher one may search long
before he will find anything which shows in explicit terms the exact
discipline of mind or system of reasoning, by which he has made it to happen
that all he has said, has so much the appearance of being truth; but a petty
remark, disconnected with the ordinary pursuits of the philosopher, may
often strikingly illustrate the operation of his mind, and the means by
which he has disciplined himself to approach as near as possible to truth;
and, such a passage occurring in this short diary, we beg to insert it. "An
anecdote of some Indians was told, that struck me very much, as holding up
but too exact a picture of many of our theories and reasonings from analogy.
Some American savages having experienced the effects of gunpowder, and
having also accidentally become masters of a small quantity of it, set
themselves to examine it, with a design of finding out what was its nature,
and how it was to be procured. The oldest and wisest of the tribe, after
considering it attentively, pronounced it to be a seed. A piece of ground
was accordingly prepared for it, and it was sown in the fullest confidence
that a great crop of it was to be produced. We smile at the mistake of these
Indians, and we do not consider, that, for the extent of their experience,
they reasoned well, and drew as logical a conclusion as many of the
philosophers of Europe. Whenever we reason only from analogy and
resemblance, and whenever we attempt to measure the nature of things by our
conceptions, we are precisely in the situation of these poor Americans." In
this Playfair exemplified the propensity to reason from certain qualities
perceived to be identical, when it is not known but that other qualities not
perceived, may be at variance. The wise American saw colour and form like
those of a seed, and from these he drew his conclusion. Had he been a
botanist, he would have discovered that the grain consisted of saltpetre and
charcoal, instead of kernel; and, whatever else he could have made of it, he
would have quickly perceived that it was not a seed. In connexion with this
it is to be held in mind, that Playfair was essentially a reasoner, and that
he was more celebrated for separating the true from the false in the
writings of others, or for establishing and applying truths accidentally
stumbled upon by others, than forextensive discoveries ofhis
own.

In 1785, Dr Adam Ferguson
exchanged the moral chair in the university for that of mathematics, taught
by professor Dugald Stewart, and, being in bad health, chose Playfair as his
assistant. He continued, however, to attend his two pupils until 1787, when
he took up his residence with his mother, who had for some time lived in
Edinburgh. He now commenced a series of papers which appeared in the
Transactions of the Royal Society of Edinburgh. The first of these was the
life of Dr Matthew Stewart, the late professor of mathematics in the
university of Edinburgh; a paper written in his usual flowing, simple, and
expressive style. A second was a paper on the causes which affect the
accuracy of Barometrical Measurements. A third was Remarks on the Astronomy
of the Brahmins. The early eastern astronomy was a subject to which he was
very partial, and to which some conceive he has paid more attention than its
importance warranted. He fought to a certain extent at disadvantage, from
ignorance of the language, and consequently of external evidence as to the
authenticity of the remarkable records containing the wisdom of the
Brahmins; but he calculated their authenticity from the circumstance, that
none but a European acquainted with the refinements of modern science could
have made the calculations on which they might have been forged. The death
of his brother James, in 1793, interrupted his philosophical pursuits, by
forcing on his management some complicated business, along with the
education of his brother’s son. In 1795, he published an edition of Euclid’s
elements for the use of his class. In this work he adopted the plan of using
algebraic signs instead of words, to render the proportions more compact and
apparent. The plan has been repeatedly practised since that period, and "Playfair’s
Euclid" is a book well known to the boys inmost mathematical
schools, by whom, however, it is not always so much admired as it is known.
In 1797 he suffered a severe attack of rheumatism, during which he sketched
an essay on the accidental discoveries which have been made by men of
science whilst in pursuit of something else, or when they had no determinate
object in view; and wrote the observations on the trigonometrical tables of
the Brahmins, and the theorems relating to the figure of the earth, which
were afterwards published in the Transactions of the Royal Society of
Edinburgh. About the same time, his friend Dr Hutton died, and Playfair, who
affectionately intended to have written his memoir, found in the study of
his works a vast field in which he afterwards distinguished himself, by the
preparation of the "Illustrations of the Huttonian Theory of the Earth." Few
observers of nature have possessed the power of describing what they have
seen, so as to make their facts and deductions perceivable to ordinary
thinkers. Playfair possessed the quality, however, to a rare extent; and it
was probably its deficiency in the works of his friend Hutton, which
prompted him to prepare the elegant and logical "Analysis of the Volcanic
Theory of the Earth,"which has been so much admired for its own
literary merits, and has been the means of rendering popular an important
theory which otherwise might have remained in obscurity. It has been said,
that the illustration of a theory of the earth was but a profitless
employment for so accurately thinking a philosopher, and that the task aught
have been left to more imaginative minds, whose speculations would have
afforded equal pleasure to those who delight in forming fabrics of theory on
insufficient foundations. It is true, that even the lucid commentary of
Playfair does not establish the Huttonian as a general and undeviating
theory, in an undoubted and indisputable situation; he seems not to have
aimed so high; and from the present state of science, no one can predicate
that the elementary formation of the earth, or even of its crust, will ever
be shown with chemical exactness. All that can be said is, that in as far as
the respective experiments and deductions of the theorists have proceeded,
the Huttonian Theory is not directly met by any fact produced on the part of
the Neptunians, and the phenomena produced in its favour strongly
show—indeed show to absolute certainty in some cases—the present formation
of a great part of the crust of the earth to have been the effect of fire,
how operating in respect to the whole substance of the globe it is
impossible to determine. The defence of a theory of the earth had for some
time been unpopular among many philosophers, from the production of such
majestic fabrics of theory as those of Whiston and Burnet, which, without a
sufficient number of ascertained facts for the analysis of the component
parts of any portion of the earth’s surfaces, showed in detail the method of
its abstraction from the rest of the universe, and the minutiae of its
formation. But Playfair never went beyond rational deduction on the facts
which were known to him, limiting the extent of his theories to reasonings
on what he knew; and it shows the accuracy of his logic, that, while the
experiments of Sir James Hall and others (which were in progress but not
complete while he wrote,) have tended to support his explication, especially
in justifying his opinion that the reason of calcination in bodies subjected
to heat was the necessity of the escape of the gases contained in them, we
are aware of none which have contradicted him.

The period between 1797 and
1802 was occupied by Mr Playfair in preparing his Illustrations, and in 1803
his biographical sketch of Hutton was published in the Society Transactions.
In 1805 he quitted the mathematical chair, and succeeded professor John
Robison in that of natural philosophy; during the same year his mother died
at the age of eighty-five, and he retired along with a younger brother, his
youngest sister, and two nephews, to Burntisland, that he might devote the
summer to uninterrupted preparation for the duties of his new class. In the
controversy with the clergymen of Edinburgh, regarding his successor to the
chair of mathematics, he took an active part. A letter which he addressed to
the provost of Edinburgh, in favour of the election of a scientific
man, as opposed to a clergyman, was answered by Dr Inglis, and from the
nature of the remarks directed against himself, he considered it necessary
to reply. The pamphlet produced under these circumstances, showed that his
calm temper might be made dangerous by interference: it is written in
considerable asperity of spirit, but without vulgar raillery or much
personality, and the serious reproof, mixed with occasional sarcasm which it
contains, shows great power to wield the weapons of literary warfare. He
next occupied himself in preparing papers on the solids of greatest
attraction, and on the progress of heat in spherical bodies, which appeared
in the Transactions of the Royal Society of Edinburgh. He also presented to
the London Royal Society, of which he was admitted a member in 1807, an
Account of the Survey of Schehallien. In 1814, he published for the use of
his students his well known Outlines of Natural Philosophy, in two volumes
octavo. The first volume of this work treats of Dynamics, Mechanics,
Hydrostatics, Hydraulics, Aerostatics, and Pneumatics. The second is devoted
to Astronomy. A third volume was intended to have embraced Optics,
Electricity, and Magnetism; but the work was never completed. In the
following year he presented to the Royal Society of Edinburgh a life of his
predecessor, professor Robison. His labours for this institution will be
perceived to have been very extensive, and they show him not to have been a
mercenary man. He was long its chief support, arranging and publishing the
Transactions, and gratuitously acting as secretary. In 1816, he published,
in the Supplement to the Encyclopaedia Britannica, a "Dissertation on the
Progress of Mathematical and Physical Science since the Revival of Letters
in Europe," a work of great erudition and research. This work interrupted a
new and much altered edition of his Illustrations of the Huttonian Theory,
which he had previously designed, but which unfortunately he was never
enabled to complete. "It was intended," says his biographer, "to commence
with a description of all the well authenticated facts in geology collected
during his extensive reading and personal observation, without any mixture
of hypothesis whatever. To this followed the general inferences which may be
deduced from the facts, an examination of the various geological systems
hitherto offered to the world, and the exclusion of those which involved any
contradiction of the principles previously ascertained; while the conclusion
would have presented the development of the system adopted by the author,
and the application of it to explain the phenomena of geology." Previously
to 1815, Mr Playfair had confined his geological observations to Britain and
Ireland; nor was he able, from causes public or private, previously to that
period, to extend them to the continent. His nephew accompanied him on a
tour which he designed to extend as far as he could through Italy,
Switzerland, and France. He spent a short time in the philosophical circle
of Paris, to which his name could not fail to be an introduction. He then
passed to Switzerland, and commenced the most important of his geological
notices at Mount Jura, where he found blocks of granite, gneiss, and mica
slate, lying loosely on the surface of mountains whose solid substance was
entirely calcareous. At Lucerne and Chamouni, he was prevented by adverse
weather, from making his intended searches among the interior valleys.
Towards winter he was about to return, when he received a letter from the
provost of Edinburgh, intimating that the patrons of the university
permitted his absence during the ensuing session—a circumstance which
enabled him to prolong his tour a whole year. After remaining for a month at
Geneva, he entered Italy by the Simplon. In the Academia del Cimento at
Florence, his enthusiasm for philosophical history was gratified by an
inspection of the instruments made by Galileo, among which was the original
telescope, made of two pieces of wood, coarsely hollowed out, and tied
together with thread. On the 12th of November he set out for Rome, which he
reached on the 18th. There he remained during the winter, occupying himself
with researches in the Vatican library, such geological observations as the
neighbourhood afforded, and the select English society always to be found in
the imperial city, among whom he found many of the friends he had met in
England. After the termination of the winter he went to Naples, where a
wider field for geological observation lay before him. The observations
which he made on this part of his route, not so much connected with the
action of the volcano as with the state of the surrounding country, are
unbodied in some interesting notes, an abstract of which may be found in the
memoir above referred to; but it is to be regretted that the amount of so
much accurate observation was not brought to bear on his Analysis of the
Theory of the Earth. Mr Playfair returned to Rome, whence, after a second
visit to Florence, he proceeded, by such gradations as enabled him
accurately to observe the mineralogy of the country, to Geneva. While
travelling through Switzerland, he visited, and prepared a short but curious
account of the Slide of Alpuach, by which trees are conveyed from the sides
of Pilatus into the lake of Lucerne, whence they proceed through the Aur to
the Rhine. On his return, he passed through Venice, Lyons, and Paris. In the
ensuing summer he retired to Burntisland, where he prepared a memoir on
Naval Tactics, in illustration of the discoveries of Clerk of Eldin, which
was published after his death. He had intended to publish in detached papers
his observations on the remarkable objects of his tour, and to have prepared
his Illustrations of the Huttonian Theory of the Earth, but he lived
scarcely long enough to commence these labours. For some years he had been
afflicted with a strangury, which alarmingly increased in the month of June,
1819, and he died on the ensuing 19th of July. He was buried on the 26th,
when the members of the Royal Medical Society, and a numerous body of public
and private friends, followed him to the grave.

The literary and domestic
character of this great and excellent man, have been drawn by Francis
Jeffrey, with whom, as the writer of many papers in the Edinburgh Review, Mr
Playfair must have been on an intimate footing. The former part of the
subject is open for the appreciation of the world, but as the latter can
only be told by one acquainted with it, we beg to extract a portion. "The
same admirable taste which is conspicuous in his writings, or rather the
higher principles from which that taste was but an emanation, spread a
similar charm over his whole life and conversation, and gave to the most
learned philosopher of his day the manners and deportment of the most
perfect gentleman. Nor was this in him the result merely of good sense and
good temper, assisted by an early familiarity with good company, and a
consequent knowledge of his own place and that of all around him. His
good-breeding was of a higher descent; and his powers of pleasing rested on
something better than mere companionable qualities. With the greatest
kindness and generosity of nature, he united the most manly firmness, and
the highest principles of honour; and the most cheerful and social
dispositions, with the gentlest and steadiest affections. Towards women, he
had always the most chivalrous feelings of regard and attention, and was,
beyond almost all men, acceptable and agreeable in their society, though
without the least levity or pretension unbecoming his age or condition. And
such, indeed, was the fascination of the perfect simplicity and mildness of
his manners, that the same tone and deportment seemed equally appropriate in
all societies, and enabled him to delight the young and the gay with the
same sort of conversation which instructed the learned and the grave. There
never, indeed, was a man of learning and talent who appeared in society so
perfectly free from all sorts of pretension, or notion of his own
importance, or so little solicitous to distinguish himself, or so sincerely
willing to give place to every one else. Even upon subjects which he had
thoroughly studied, he was never in the least impatient to speak, and spoke
at all times without any tone of authority; while so far from wishing to set
off what he had to say by any brilliancy or emphasis or expression, it
seemed generally as if he had studied to disguise the weight and originality
of his thoughts under the plainest form of speech, and the most quiet and
indifferent manner; so that the profoundest remarks and subtlest
observations were often dropped, not only without any solicitude that their
value should be observed, but without any apparent consciousness that they
possessed any."

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